This invention relates to fluoride including waste water processing method and device. The fluoride including waste water is drained from such as factories for manufacturing semiconductor, factories for processing metal surface, factories for manufacturing stainless, and factories for manufacturing ceramics.
1. Description of the Related Art
In the manner which will be described more in detail, a conventional fluoride including waste water processing method comprises a reaction processing step of adding calcium compound in fluoride including waste water which is received in a reaction vessel while the fluoride including waste water is aggregated and of reacting the calcium compound with fluoride of the fluoride including waste water to generate calcium fluoride, a sedimentation processing step of adding coagulant in the fluoride including waste water which is sent to a sedimentation vessel from the reaction vessel and which is aggregated to sediment the calcium fluoride, and a supernatant liquid draining step of draining supernatant liquid of the fluoride including waste water from the sedimentation vessel.
Another conventional fluoride including waste water processing methods are disclosed in Japanese Unexamined Patent Publications (koukai) No. 241988/1985 and No. 166083/1985 and Japanese Examined Patent Publication (koukoku) No. 2675511989. Each of these methods comprises a reaction processing step of adding calcium compound in fluoride including waste water which is received in a reaction vessel while the fluoride including waste water is aggregated and of reacting the calcium compound with fluoride of the fluoride including waste water to generate calcium fluoride, a sedimentation processing step of adding coagulant in the fluoride including waste water which is sent to a sedimentation vessel from the reaction vessel and which is aggregated to sediment the calcium fluoride, a sending back processing step of sending back the calcium fluoride, and a supernatant liquid draining step of draining supernatant liquid of the fluoride including waste water from the sedimentation vessel.
Also, further conventional fluoride including waste water processing methods are disclosed in Japanese Unexamined Patent Publications (koukai) No. 185073/1993 and No. 241988/1985. Each of these methods comprises a step of adding one of high molecular coagulant, ferric salt, and aluminium salt in a time of adding calcium compound in fluoride including waste water which is received in a reaction vessel.
In addition, a conventional organic waste water processing device is disclosed in Japanese Unexamined Patent Publication (koukai) No. 113362/1976. This conventional organic waste water processing device comprises means for reacting, by aeration, organic matter in organic waste water with microbes in activated sludge in a reaction vessel, means for sedimenting the activated sludge in a sedimentation basin after aeration to abstract the activated sludge from the organic matter, and means for sending back the activated sludge which is abstract from organic matter to the reaction vessel.
However, in the conventional fluoride including waste water processing methods, it is difficult that the fluoride including waste water becomes to have concentration of fluoride that is a value less than 5 mg/litre. Also, in the conventional fluoride including waste water processing methods, it is difficult that the fluoride including waste water in the reaction vessel becomes to have concentration of calcium fluoride that is a value more than 2%. In addition, since, in the conventional fluoride including waste water processing methods, it needs to hold high concentration of calcium fluoride of the fluoride including waste water in the reaction vessel, great volume of water for sending back the calcium fluoride to the reaction vessel from the sedimentation vessel is needed.